U.S. patent application number 15/846000 was filed with the patent office on 2019-06-20 for sensor assembly with cleaning system.
This patent application is currently assigned to Ford Global Technologies, LLC. The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Syed K. Ali, Venkatesh Krishnan, Andre Sykula, Dhaval P. Vaishnav, Yi-Hsin Yen.
Application Number | 20190184942 15/846000 |
Document ID | / |
Family ID | 66674509 |
Filed Date | 2019-06-20 |
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United States Patent
Application |
20190184942 |
Kind Code |
A1 |
Vaishnav; Dhaval P. ; et
al. |
June 20, 2019 |
SENSOR ASSEMBLY WITH CLEANING SYSTEM
Abstract
A sensor assembly includes a cylindrical sensor window defining
an axis, and an annular member coupled to the sensor window and
rotatable about the axis. The annular member includes a nozzle
aimed at the sensor window and oriented at an acute angle from a
radial direction toward the axis in a plane orthogonal to the
axis.
Inventors: |
Vaishnav; Dhaval P.;
(Canton, MI) ; Yen; Yi-Hsin; (Canton, MI) ;
Ali; Syed K.; (Dearborn, MI) ; Sykula; Andre;
(Sterling Heights, MI) ; Krishnan; Venkatesh;
(Canton, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies,
LLC
Dearborn
MI
|
Family ID: |
66674509 |
Appl. No.: |
15/846000 |
Filed: |
December 18, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60S 1/62 20130101; G02B
27/0006 20130101; B60S 1/566 20130101; G01S 7/4813 20130101; G01S
17/931 20200101; B08B 1/006 20130101; B60S 1/544 20130101; G01S
2007/4977 20130101; H04L 67/12 20130101; B08B 3/024 20130101; B60S
1/0848 20130101; G05D 1/0088 20130101; G01S 7/497 20130101; B08B
1/04 20130101; B60S 1/528 20130101; B60S 1/54 20130101; B60S 1/56
20130101 |
International
Class: |
B60S 1/08 20060101
B60S001/08; B08B 1/00 20060101 B08B001/00; B08B 1/04 20060101
B08B001/04; B60S 1/56 20060101 B60S001/56; G05D 1/00 20060101
G05D001/00; H04L 29/08 20060101 H04L029/08; B60S 1/52 20060101
B60S001/52; G02B 27/00 20060101 G02B027/00; B60S 1/54 20060101
B60S001/54; B60S 1/62 20060101 B60S001/62 |
Claims
1. A sensor assembly comprising: a cylindrical sensor window
defining an axis; and an annular member coupled to the sensor
window and rotatable about the axis, the annular member including a
nozzle aimed at the sensor window and oriented at an acute angle
from a radial direction toward the axis in a plane orthogonal to
the axis.
2. The sensor assembly of claim 1, wherein the nozzle is a first
nozzle, the acute angle is a first acute angle, and the annular
member includes a second nozzle aimed at the sensor window and
oriented at a second acute angle from a radial direction toward the
axis in a plane orthogonal to the axis.
3. The sensor assembly of claim 1, further comprising a base member
fixed relative to the sensor window and about which the annular
member extends, wherein the annular member includes an
annular-member passage fluidly connected to the nozzle, and the
base member includes a base-member passage fluidly connected to the
annular-member passage.
4. The sensor assembly of claim 3, wherein the base-member passage
is fluidly connected to the annular-member passage for rotational
positions continuously for 360.degree. of the annular member
relative to the base member.
5. The sensor assembly of claim 3, wherein the annular-member
passage extends about and is partially defined by the base
member.
6. The sensor assembly of claim 5, wherein the base-member passage
is elongated to an opening connected to the annular-member
passage.
7. The sensor assembly of claim 3, wherein the nozzle is a liquid
nozzle, the base-member passage is a liquid base-member passage,
and the base member includes an air nozzle aimed at the sensor
window and an air base-member passage separate from the liquid
base-member passage.
8. The sensor assembly of claim 7, further comprising a pump and a
compressor, wherein the liquid base-member passage is fluidly
connected to the pump, and the air base-member passage is fluidly
connected to the compressor.
9. The sensor assembly of claim 1, further comprising a pump
fluidly connected to the nozzle, wherein the pump is sized to
produce sufficient pressure for fluid exiting the nozzle to cause
the annular member to rotate.
10. The sensor assembly of claim 1, wherein the nozzle is a liquid
nozzle, the sensor assembly further comprising a base member fixed
relative to the sensor window, wherein the base member includes an
air nozzle aimed at the sensor window.
11. The sensor assembly of claim 10, wherein the base member
includes a plurality of air nozzles including the air nozzle, the
air nozzles circumferentially arranged about the sensor window.
12. The sensor assembly of claim 1, further comprising a mounting
bracket connectable to a vehicle, wherein the sensor window is
fixed relative to the mounting bracket.
13. The sensor assembly of claim 1, wherein the sensor window is a
first sensor window, and the first sensor window is disposed above
the annular member, the sensor assembly further comprising a second
cylindrical sensor window fixed relative to the first sensor window
and disposed below the annular member.
14. The sensor assembly of claim 13, wherein the nozzle is a first
nozzle, the acute angle is a first acute angle, and the annular
member includes a second nozzle aimed at the second sensor window
and oriented at a second acute angle from a radial direction toward
the axis in a plane orthogonal to the axis.
15. The sensor assembly of claim 14, wherein the first acute angle
is equal to the second acute angle.
16. The sensor assembly of claim 14, wherein the first nozzle is a
first liquid nozzle, the second nozzle is a second liquid nozzle,
the sensor assembly further comprising a base member fixed relative
to the first sensor window, wherein the base member includes a
first air nozzle aimed at the first sensor window and a second air
nozzle aimed at the second sensor window.
17. The sensor assembly of claim 1, wherein the acute angle is
between 15.degree. and 45.degree..
18. The sensor assembly of claim 1, wherein the annular member is
rotatingly drivable only by fluid exiting the nozzle.
19. A sensor assembly comprising: a cylindrical sensor window
defining an axis; an annular member coupled to the sensor window
and rotatable about the axis; means for washing the sensor window;
and means for rotating the annular member about the axis, wherein
the means for rotating the annular member about the axis are the
same as the means for washing the sensor window.
20. The sensor assembly of claim 19, further comprising means for
drying the sensor window.
Description
BACKGROUND
[0001] Autonomous vehicles include a variety of sensors. Some
sensors detect internal states of the vehicle, for example, wheel
speed, wheel orientation, and engine and transmission variables.
Some sensors detect the position or orientation of the vehicle, for
example, global positioning system (GPS) sensors; accelerometers
such as piezo-electric or microelectromechanical systems (MEMS);
gyroscopes such as rate, ring laser, or fiber-optic gyroscopes;
inertial measurements units (IMU); and magnetometers. Some sensors
detect the external world, for example, radar sensors, scanning
laser range finders, light detection and ranging (LIDAR) devices,
and image processing sensors such as cameras. A LIDAR device
detects distances to objects by emitting laser pulses and measuring
the time of flight for the pulse to travel to the object and back.
Some sensors are communications devices, for example,
vehicle-to-infrastructure (V2I) or vehicle-to-vehicle (V2V)
devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] FIG. 1 is a side view of an example vehicle including an
example sensor assembly.
[0003] FIG. 2 is a front view of the vehicle including the sensor
assembly.
[0004] FIG. 3 is a perspective view of the sensor assembly.
[0005] FIG. 4 is a top view of the sensor assembly.
[0006] FIG. 5 is a cross-sectional side view of the sensor
assembly.
[0007] FIG. 6 is another cross-sectional side view of the sensor
assembly.
[0008] FIG. 7 is a cross-sectional top view of the sensor
assembly.
[0009] FIG. 8 is another cross-sectional top view of the sensor
assembly.
[0010] FIG. 9 is a diagram of a cleaning system for the sensor
assembly.
DETAILED DESCRIPTION
[0011] A sensor assembly includes a cylindrical sensor window
defining an axis, and an annular member coupled to the sensor
window and rotatable about the axis. The annular member including a
nozzle aimed at the sensor window and oriented at an acute angle
from a radial direction toward the axis in a plane orthogonal to
the axis.
[0012] The nozzle may be a first nozzle, the acute angle may be a
first acute angle, and the annular member may include a second
nozzle aimed at the sensor window and oriented at a second acute
angle from a radial direction toward the axis in a plane orthogonal
to the axis.
[0013] The sensor assembly may further include a base member fixed
relative to the sensor window and about which the annular member
extends. The annular member may include an annular-member passage
fluidly connected to the nozzle, and the base member may include a
base-member passage fluidly connected to the annular-member
passage. The base-member passage may be fluidly connected to the
annular-member passage for rotational positions continuously for
360.degree. of the annular member relative to the base member.
[0014] The annular-member passage may extend about and be partially
defined by the base member. The base-member passage may be
elongated to an opening connected to the annular-member
passage.
[0015] The nozzle may be a liquid nozzle, the base-member passage
may be a liquid base-member passage, and the base member may
include an air nozzle aimed at the sensor window and an air
base-member passage separate from the liquid base-member passage.
The sensor assembly may further include a pump fluidly connected to
the nozzle, and the pump may be sized to produce sufficient
pressure for fluid exiting the nozzle to cause the annular member
to rotate.
[0016] The nozzle may be a liquid nozzle. The sensor assembly may
further include a base member fixed relative to the sensor window,
and the base member may include an air nozzle aimed at the sensor
window. The base member may include a plurality of air nozzles
including the air nozzle, and the air nozzles may be
circumferentially arranged about the sensor window.
[0017] The sensor assembly may further include a mounting bracket
connectable to a vehicle, and the sensor window may be fixed
relative to the mounting bracket.
[0018] The sensor window may be a first sensor window, and the
first sensor window may be disposed above the annular member. The
sensor assembly may further include a second cylindrical sensor
window fixed relative to the first sensor window and disposed below
the annular member. The nozzle may be a first nozzle, the acute
angle may be a first acute angle, and the annular member may
include a second nozzle aimed at the second sensor window and
oriented at a second acute angle from a radial direction toward the
axis in a plane orthogonal to the axis. The first acute angle may
be equal to the second acute angle. The first nozzle may be a first
liquid nozzle, the second nozzle may be a second liquid nozzle, and
the sensor assembly may further include a base member fixed
relative to the first sensor window. The base member may include a
first air nozzle aimed at the first sensor window and a second air
nozzle aimed at the second sensor window.
[0019] The acute angle may be between 15.degree. and
45.degree..
[0020] The annular member may be rotatingly drivable only by fluid
exiting the nozzle.
[0021] A sensor assembly includes a cylindrical sensor window
defining an axis, an annular member coupled to the sensor window
and rotatable about the axis, means for washing the sensor window,
and means for rotating the annular member about the axis. The means
for rotating the annular member about the axis are the same as the
means for washing the sensor window.
[0022] The sensor assembly may further include means for drying the
sensor window.
[0023] As best seen in FIG. 3, a sensor assembly 30 includes a
cylindrical first sensor window 32 defining an axis A, and an
annular member 34 coupled to the first sensor window 32 and
rotatable about the axis A. The annular member 34 includes a first
liquid nozzle 36 aimed at the first sensor window 32 and oriented
at an acute first angle .theta. (see FIG. 4) from a radial
direction R toward the axis A in a plane P orthogonal to the axis
A. (The adjectives "first" and "second" are used throughout this
document as identifiers and are not intended to signify importance
or order.)
[0024] The sensor assembly 30 can provide more complete coverage
when cleaning the first sensor window 32 than a system using
stationary nozzles. At the same time, the sensor assembly 30 can
use fewer first liquid nozzles 36 than a system using stationary
nozzles, which can lower the necessary pressure of the fluid
exiting the first liquid nozzles 36, reduce fluid consumption, and
lower required power for a pump 86 supplying the first liquid
nozzles 36. The sensor assembly 30 can cause the annular member 34
to rotate without using a motor or the like, reducing the
complexity and cost of the sensor assembly 30.
[0025] With reference to FIGS. 1 and 2, the sensor assembly 30 is
included on a vehicle 38. The vehicle 38 may be an autonomous or
semi-autonomous vehicle. A computer (not shown) can be configured
to operate the vehicle 38 independently of the intervention of a
human driver, completely or to a lesser degree. The computer may be
programmed to operate one or more of the propulsion, brake system,
steering, and/or other vehicle systems. The vehicle 38 is
considered fully autonomous if the computer operates each, i.e.,
all, of the propulsion, brake system, and steering.
[0026] With reference to FIG. 3, the sensor assembly 30 may include
a mounting bracket 40 connectable to the vehicle 38. For example,
the mounting bracket 40 may be attached to a casing 42 that
supports and houses a plurality of sensors 44, 46, 47, as shown in
FIGS. 1, 2, 5, and 6. The mounting bracket 40 may be elongated
vertically relative to the vehicle 38. The mounting bracket 40 may
be a rigid structure that supports the rest of the sensor assembly
30 at a height from the rest of the vehicle 38. The mounting
bracket 40 may be integral with, i.e., a single piece with, the
casing 42, or the mounting bracket 40 may be a separate piece that
is fixedly attached to the casing 42, e.g., via conventional
attachment means, such as adhesives, fasteners, snaps, etc.
[0027] The sensor assembly 30 includes the sensors 44, 46, 47. The
sensors 44, 46, 47 may provide data about operation of the vehicle
38, for example, wheel speed, wheel orientation, and engine and
transmission data (e.g., temperature, fuel consumption, etc.). The
sensors 44, 46, 47 may detect the location and/or orientation of
the vehicle 38. For example, the sensors 44, 46, 47 may include
global positioning system (GPS) sensors; accelerometers such as
piezo-electric or microelectromechanical systems (MEMS); gyroscopes
such as rate, ring laser, or fiber-optic gyroscopes; inertial
measurements units (IMU); and magnetometers. The sensors 44, 46, 47
may detect the external world, e.g., objects and/or characteristics
of surroundings of the vehicle 38, such as other vehicles, road
lane markings, traffic lights and/or signs, pedestrians, etc. For
example, the sensors 44, 46, 47 may include radar sensors, scanning
laser range finders, light detection and ranging (LIDAR) devices,
and image processing sensors such as cameras.
[0028] A base member 48 is fixed relative to the mounting bracket
40. The base member 48 may be directly or indirectly attached to
the mounting bracket 40. The base member 48 may have a cylindrical
shape. The base member 48 may have a disc-like shape with a
diameter longer than an axial height. The base member 48 may have a
groove 104 on an outer periphery of the base member 48.
[0029] With reference to FIGS. 5 and 6, the sensors 44, 46, 47 may
include a first sensor 44 and a second sensor 46. The first and
second sensors 44, 46 may be LIDAR devices. A LIDAR device detects
distances to objects by emitting laser pulses at a particular
wavelength and measuring the time of flight for the pulse to travel
to the object and back. The first and second sensors 44, 46 are
fixed relative to the mounting bracket 40 and may be attached,
directly or via another component, to the mounting bracket 40. The
first and second sensors 44, 46 may be positioned along the axis A.
The first sensor 44 may be positioned above the second sensor 46.
The first sensor 44 may be positioned above the base member 48, and
the second sensor 46 may be positioned below the base member
48.
[0030] A first housing 50 may encase the first sensor 44, and a
second housing 52 may encase the second sensor 46. The housings 50,
52 may each have a cylindrical shape with a top cap 54, a bottom
cap 56, and a sensor window 32, 58. The top cap 54 is above, i.e.,
in a vehicle-upward direction from, the sensor window 32, 58, and
the bottom cap 56 is below, i.e., in a vehicle-downward direction
from, the sensor window 32, 58. The bottom cap 56 of the first
housing 50 and the top cap 54 of the second housing 52 may be
attached to the base member 48, and the mounting bracket 40 may
support the housings 50, 52 via the base member 48. Each housing
50, 52 has a side surface 60 that includes an outside of the sensor
window 32, 58 and circumferentially extending sides of the top cap
54 and the bottom cap 56. The cylindrical shape of the housings 50,
52 defines the axis A, which runs through a center of the housings
50, 52. The axis A is oriented vertically relative to the vehicle
38.
[0031] The sensor windows 32, 58 include a first sensor window 32
in the first housing 50 and a second sensor window 58 in the second
housing 52. The sensor windows 32, 58 are fixed relative to the
mounting bracket 40, such as through the base member 48 and the
housings 50, 52. The sensor windows 32, 58 are cylindrical and may
also define the axis A. The sensor windows 32, 58 extend about the
axis A. The sensor windows 32, 58 may extend fully about the axis
A, that is, 360.degree., or partially about the axis A. The sensor
windows 32, 58 extend along the axis A from respective bottom edges
62 to respective top edges 64. The sensor windows 32, 58 have
diameters, which may be equal. The diameter of each sensor window
32, 58 may be the same as the rest of the side surface 60 of the
respective housing, if any; in other words, the sensor windows 32,
58 may be flush or substantially flush with the side surfaces 60.
"Substantially flush" means a seam between the sensor window 32, 58
and the rest of the side surface 60 does not cause turbulence in
air flowing along the side surface 60. At least some of each sensor
window 32, 58 is transparent with respect to whatever medium the
first and second sensors 44, 46 are capable of detecting. For
example, if the first and second sensors 44, 46 are LIDAR devices,
then the sensor windows 32, 58 are transparent with respect to
light at the wavelength generated by lasers of the first and second
sensors 44, 46.
[0032] The annular member 34 extends circumferentially about the
base member 48 relative to the axis A. The annular member 34 is
annularly shaped. The first housing 50 and the first sensor window
32 are disposed above the annular member 34, and the second housing
52 and the second sensor window 58 are disposed below the annular
member 34. The annular member 34 has an inner diameter and an outer
diameter. The inner diameter may be larger than the diameter of the
first housing 50 and larger than the diameter of the second housing
52.
[0033] The annular member 34 is rotatable about the axis A. The
annular member 34 may be rotatably coupled to the base member 48,
e.g., via a bearing (not shown) or the like. The annular member 34
is thus rotatably coupled to the sensor windows 32, 58. The annular
member 34 may have a projected surface 106 on an inner periphery of
the annular member 34. The projected surface 106 may be engageable
with the groove 104 of the base member 48. The annular member 34
and the base member 48 may be rotatably engageable via the groove
104 and the projected surface 106. The groove 104 and the projected
surface 106 may help the annular member 34 and the base member 48
align with each other. The annular member 34 may be able to rotate
relative to the rest of the vehicle 38 while the mounting bracket
40, the base member 48, and the housings 50, 52 remain still
relative to the rest of the vehicle 38.
[0034] With reference to FIG. 9, an air system 66 of the vehicle 38
includes a compressor 68, an air nonreturn valve 100, an air supply
line 70, an air base-member passage 72, and air nozzles 78, 80. The
compressor 68 and the air nozzles 78, 80 are fluidly connected to
each other (i.e., fluid can flow from one to the other) through the
air supply line 70 and the air base-member passage 72 in
sequence.
[0035] The compressor 68 increases the pressure of a gas by
reducing a volume of the gas or by forcing additional gas into a
constant volume. The compressor 68 may be any suitable type of
compressor, e.g., a positive-displacement compressor such as a
reciprocating, ionic liquid piston, rotary screw, rotary vane,
rolling piston, scroll, or diaphragm compressor; a dynamic
compressor such as an air bubble, centrifugal, diagonal,
mixed-flow, or axial-flow compressor; or any other suitable
type.
[0036] The air nonreturn valve 100 may be located between the
compressor 68 and the air supply line 70 or in a middle of the air
supply line 70, i.e., spaced from ends of the air supply line 70.
The air nonreturn valve 100 may be positioned to prevent airflow
through the air supply line 70 away from the base member 48 toward
the compressor 68, i.e., to prevent backflow. The air nonreturn
valve 100 may be any suitable type of nonreturn valve, e.g., a ball
check valve, a diaphragm check valve, a swing check valve, a stop
check valve, a lift check valve, an inline check valve, a duckbill
valve, a pneumatic nonreturn valve, etc. The air nonreturn valve
100 can improve the response time for supplying airflow through the
air nozzles 78, 80 by keeping pressurized air in the air supply
line 70 and air base-member passage 72. The air nonreturn valve 100
can improve the modularity of the sensor assembly 30 by allowing
the sensor assembly 30 to be detached at the air nonreturn valve
100 from the vehicle 38 and reattached to the vehicle 30.
[0037] The air supply line 70 extends from the compressor 68 to the
air base-member passage 72. The air supply line 70 may be, e.g., a
flexible tube.
[0038] With reference to FIGS. 6 and 8, the base member 48 includes
the air base-member passage 72. The air base-member passage 72 is a
tube system including an air inlet tube 74 receiving gas from the
air supply line 70 and air outlet tubes 76 branching from the air
inlet tube 74 to the air nozzles 78, 80. The air outlet tubes 76
may extend horizontally, as best seen in FIG. 8, and then
vertically, i.e., up and down, as best seen in FIG. 6. The air
base-member passage 72 may be material of the base member 48
defining space for gas to flow.
[0039] The sensor assembly 30 includes means for drying the sensor
windows 32, 58. For example, the base member 48 as illustrated
includes a plurality of the air nozzles 78, 80 aimed at one or both
of the sensor windows 32, 58. The air nozzles 78, 80 may include
one or more first air nozzles 78 aimed at the first sensor window
32 and one or more second air nozzles 80 aimed at the second sensor
window 58. The air nozzles 78, 80 are arranged circumferentially
about the sensor windows 32, 58. For example, as shown in FIGS. 4,
6, and 8, four first air nozzles 78 are substantially equally
spaced at a radius from the axis A and aimed at the first sensor
window 32, and four second air nozzles 80 are equally spaced at the
radius from the axis A and aimed at the second sensor window 58.
Different numbers of air nozzles 78, 80 and different distances
from the axis A may be used, e.g., to ensure uniform airflow
through all the air nozzles 78, 80.
[0040] With reference to FIG. 9, a liquid system 82 of the vehicle
38 includes a reservoir 84, the pump 86, a liquid nonreturn valve
102, a liquid supply line 88, a liquid base-member passage 90, an
annular-member passage 92, and the liquid nozzles 36, 94. The
reservoir 84, the pump 86, and the liquid nozzles 36, 94 are
fluidly connected to each other (i.e., fluid can flow from one to
the other) via the liquid supply line 88, the liquid base-member
passage 90, and the annular-member passage 92 in sequence. The
liquid system 82 distributes washer fluid stored in the reservoir
84 to the liquid nozzles 36, 94. "Washer fluid" in this context
refers to any liquid stored in the reservoir 84 for cleaning. The
washer fluid may include solvents, detergents, diluents such as
water, etc.
[0041] The reservoir 84 may be a tank fillable with liquid, e.g.,
washer fluid for window cleaning. The reservoir 84 may be disposed
in a front of the vehicle 38, specifically, in an engine
compartment forward of a passenger cabin. The reservoir 84 may
store the washer fluid only for supplying the sensor assembly 30 or
also for other purposes, such as supply to a windshield.
[0042] The pump 86 may force the washer fluid through the liquid
supply line 88 to the liquid base-member passage 90 with sufficient
pressure that the washer fluid sprays from the liquid nozzles 36,
94. The pump 86 is fluidly connected to the reservoir 84. The pump
86 may be attached to or disposed in the reservoir 84. The pump 86
is sized to produce sufficient pressure for fluid exiting the
liquid nozzles 36, 94 to cause the annular member 34 to rotate, as
described below.
[0043] The liquid nonreturn valve 102 may be located between the
pump 86 and the liquid supply line 88 or in a middle of the liquid
supply line 88, i.e., spaced from ends of the liquid supply line
88. The liquid nonreturn valve 102 may be positioned to prevent
fluid flow through the liquid supply line 88 away from the annular
member 34 toward the pump 86, i.e., to prevent backflow. The liquid
nonreturn valve 102 may be any suitable type of nonreturn valve,
e.g., a ball check valve, a diaphragm check valve, a swing check
valve, a stop check valve, a lift check valve, an inline check
valve, a duckbill valve, a pneumatic nonreturn valve, etc. The
liquid nonreturn valve 102 can improve the response time for
supplying fluid through the liquid nozzles 36, 94 by keeping fluid
in the liquid supply line 88, the liquid base-member passage 90,
and the annular-member passage 92. The liquid nonreturn valve 102
can improve the modularity of the sensor assembly 30 by allowing
the sensor assembly 30 to be detached at the liquid nonreturn valve
102 from the vehicle 38 and reattached to the vehicle 30.
[0044] The liquid supply line 88 extends from the pump 86 to the
liquid base-member passage 90. The liquid supply line 88 may be,
e.g., a flexible tube.
[0045] With reference to FIGS. 5 and 7, the base member 48 includes
the liquid base-member passage 90. The liquid base-member passage
90 is a tube system including a liquid inlet tube 96 receiving
fluid from the liquid supply line 88 and liquid outlet tubes 98
branching from the liquid inlet tube 96 to the annular-member
passage 92. The liquid base-member passage 90 may be material of
the base member 48 defining space for fluid to flow. The liquid
base-member passage 90 is separate from the air base-member passage
72; in other words, the liquid base-member passage 90 and the air
base-member passage 72 are not fluidly connected, i.e., material of
the base member 48 separates the liquid base-member passage 90 from
the air base-member passage 72.
[0046] The annular member 34 includes the annular-member passage
92. The annular-member passage 92 is fluidly connected to the
liquid base-member passage 90 and to the liquid nozzles 36, 94. The
liquid base-member passage 90 is fluidly connected to the
annular-member passage 92 for rotational positions continuously for
360.degree. of the annular member 34 relative to the base member
48; in other words, the liquid base-member passage 90 is fluidly
connected to the annular-member passage 92 at any position of the
annular member 34 as the annular member 34 rotates about the axis
A. The annular-member passage 92 extends about and is partially
defined by the base member 48. The annular-member passage 92 may be
material of the annular member 34 and of the base member 48
defining a space for fluid to flow.
[0047] The sensor assembly 30 includes means for washing the sensor
windows 32, 58 and means for rotating the annular member 34 about
the axis A. The means for rotating the annular member 34 about the
axis A are the same as the means for washing the sensor windows 32,
58.
[0048] For example, the annular member 34 includes a plurality of
the liquid nozzles 36, 94 aimed at one or both of the sensor
windows 32, 58. The liquid nozzles 36, 94 are arranged
circumferentially about the sensor windows 32, 58. For example, as
shown in FIGS. 4, 5, and 7, two liquid nozzles 36, 94 are equally
spaced at a radius from the axis A and aimed at the first sensor
window 32, and two liquid nozzles 36, 94 are equally spaced at the
radius from the axis A and aimed at the second sensor window 58.
Different numbers of liquid nozzles 36, 94 and different distances
from the axis A may be used; for example, a single liquid nozzle 36
may be aimed at the first sensor window 32, and a single liquid
nozzle 36 may be aimed at the second sensor window 58.
[0049] With reference to FIG. 4, each liquid nozzle 36, 94 is aimed
at one of the sensor windows 32, 58 and oriented at an acute angle
from a radial direction R toward the axis A in a plane P orthogonal
to the axis A. For the purposes of this disclosure, a radial
direction toward an axis means the direction of the shortest
distance to the axis. For example, as shown in FIG. 4, a first
liquid nozzle 36 may be aimed at the first sensor window 32 and
oriented at an angle .theta. from the radial direction R, and a
second liquid nozzle 94 may be aimed at the first sensor window 32
and oriented at an angle .phi. from the radial direction R. The
first and second liquid nozzles 36, 94 may also be oriented upward
or downward from the plane P orthogonal to the axis A. The angles
.theta., .phi. are acute and may be equal. The angles .theta.,
.phi. may be between 15.degree. and 45.degree., resulting in the
pressure of the fluid exiting the liquid nozzles 36, 94 causing the
annular member 34 to rotate while the fluid exiting the liquid
nozzles 36, 94 lands on the sensor windows 32, 58.
[0050] In operation, the annular member 34 is rotatingly drivable
by fluid exiting the liquid nozzles 36, 94. The pump 86 draws fluid
from the reservoir 84 and sends the fluid through the liquid supply
line 88, the liquid base-member passage 90, and the annular-member
passage 92. The force of the fluid exiting the liquid nozzles 36,
94 pushes the annular member 34 in a circumferential direction
opposite the circumferential direction in which the liquid nozzles
36, 94 are aimed, in other words, in a counterclockwise direction
as seen in FIG. 4. As the annular member 34 rotates for a complete
revolution, the fluid exiting the liquid nozzles 36, 94 lands on
360.degree. of the sensor windows 32, 58. The annular member 34 may
be rotatingly drivable only by fluid exiting the liquid nozzles 36,
94; in other words, no motor or the like assists the fluid exiting
the liquid nozzles 36, 94 to rotate the annular member 34.
[0051] The disclosure has been described in an illustrative manner,
and it is to be understood that the terminology which has been used
is intended to be in the nature of words of description rather than
of limitation. Many modifications and variations of the present
disclosure are possible in light of the above teachings, and the
disclosure may be practiced otherwise than as specifically
described.
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